The present invention relates to a fuel processor for a fuel cell arrangement and a method of operating a fuel processor for a fuel cell arrangement.
It is known from European patent EP0673074B1 to provide a fuel cell arrangement comprising a pre-reformer, which is supplied with anode off gas containing hydrogen and steam from the fuel cells and which is supplied with a hydrocarbon fuel. The pre-reformer comprises a catalyst suitable for low temperature steam reforming of the hydrocarbon fuel and a catalyst for partial oxidation reforming of the hydrocarbon fuel. The pre-reformer also comprises a catalyst suitable for hydrodesulphurisation of the hydrocarbon fuel.
A problem with this arrangement is that at low electrical load conditions, or at open circuit conditions, of the fuel cell arrangement, the fuel cells do not generate steam for the low temperature steam reforming reaction. A further problem with this arrangement is that the hydrodesulphurisation of the hydrocarbon fuel is dependent on the rate of anode off gas, hydrogen, recirculation and this is dependent upon the operating conditions of the fuel cell arrangement.